The present invention relates to novel collapsible containers having laminated tubes and methods for making such containers. The containers of the present invention are characterized by soft shoulders that facilitate removal of the contents of the containers and a three-piece construction that permits the economical manufacture of containers having a number of different diameters. Preferred containers of the present invention include tamper proof closure members.
Collapsible containers having laminated tubes are, of course, well known in the art. One prior art construction is described in U.S. Pat. No. 3,172,571 to Marchak. In the Marchak container, a thermoplastic headpiece is injection molded onto a laminated tube. The molded headpiece comprises a neck portion, which is threaded to receive a screw-on cap, and a skirt or shoulder portion which is bonded to the upper portion of the laminated tube during the injection molding process. Different injection molding apparatus must be constructed and used to make containers having laminated tubes of different diameters.
The laminated tube in the Marchak container may be constructed so that it is impermeable to moisture, oxygen and volatile oils. According to Marchak, the purpose of using such an impermeable tube is to prevent the passage of volatile oils and moisture from the product in the container through the tube to the exterior of the container.
A problem with the Marchak container is that the thermoplastic shoulder portion of the container, unlike the tube itself, is not laminated and is relatively permeable to moisture and oxygen. U.S. Pat. Nos. 3,260,777 and 3,295,725 to Brandt, U.S. Pat. Nos. 3,565,293, 4,185,757 and 4,338,278 to Schultz and U.S. Pat. No. 3,260,411 to Dobson all describe efforts to solve this problem. These patents describe collapsible containers having an impermeable insert embedded into or bonded to the shoulder portion of a thermoplastic headpiece. In each of the containers described in the Brandt, Schultz and Dobson patents, a thermoplastic headpiece is injection molded and simultaneously bonded to the laminated tube of the container. Accordingly, as with the Marchak container, the Brandt, Schultz and Dobson containers require the use of different injection molding apparatus to make headpieces suitable for containers having tubes of different diameters.
Beginning in the 1960's and until recently, virtually all collapsible laminated toothpaste tubes sold in the United States have been manufactured by techniques, like those described in the Marchak, Brandt, Schultz and Dobson patents, in which a thermoplastic headpiece is injection molded and simultaneously bonded to the tube portion of the container. More recently, however, tubes have been sold that are manufactured from a molded headpiece, laminated tube, and a laminated shoulder insert, all of which were pre-formed and joined together in a separate bonding step. Tubes of this type are described in West German Patentschrift DE No. 3042073 C2 (the German patent). In FIGS. 1 and 2 of the German patent, the molded headpiece is numbered 2, the laminated shoulder insert is numbered 3, and the laminated tube is numbered 1. During the bonding step, both the insert and tube are bonded to the molded headpiece. In the constructions depicted in the German patent, different headpieces must be molded for tubes of different diameters.
U.S. Pat. No. 4,132,331 to Magerlee also describes collapsible containers in which a molded headpiece, laminated tube and a laminated shoulder insert are pre-formed and joined together in a separate bonding step or steps. I understand that the collapsible container depicted in FIG. 4 of the Magerlee patent has been sold in Europe and possibly elsewhere. In that container, the shoulder insert, which is referred to as "connecting body 60", is inserted between the "tube pipe 2" and the shoulder portion of the "head part 62" as depicted in FIG. 4. Layers 64 and 66 of the connecting body 60 are "hot-sealing layers" so that upon the application of heat and pressure the opposite sides of these layers can be bonded to the tube pipe and shoulder portion of the head part, respectively. It is apparent from FIG. 4 of the Magerlee patent that different "head parts" must be molded for tubes of different diameters.
In another embodiment described in the Magerlee patent and depicted in FIG. 3 of that patent, the upper portion on of the connecting body is formed into a cylindrical neck part that is inserted into an annular groove in the head of the container. As can be seen from FIG. 3, in this embodiment both the major surfaces of the upper portion of the connecting body abut the head of the container. Inserting a connecting body into an annular groove in the head of the container would appear to present difficulties that would make the container depicted in FIG. 3 commercially impracticable.